Such machines, which in the working position of the carrying beam the mower supporting mount is positioned generally perpendicular to the forward movement of the machine, are commonly known. Since mowers considerably extend beyond the greatest width of the tractor, there must be a reduction in width in order to transport in a transport position, which generally is accomplished by means of a horizontal swinging behind the tractor about a vertical pivot axis. In order to swing into the working position the mower must be locked in place, since it otherwise freely swings back and forth between its working and transport positions.
If the mower encounters an obstacle in its working position, to avoid heavy damage, it may be swung into its transport position. In European Pat. No. 0022283 this object is already made known, which has a mowing device attached to a mounting beam that is upwardly swingable about a pivot axle, so that before striking an obstacle the mower device carrying beam can swing against the bias of a spring mechanism.
With such swinging action caused before encountering small masses, a part of the mower must act before the encounter with an obstacle, since otherwise damage to the carrier beam follows unless the action avoiding the smallest impact is followed. Further this known apparatus of the tractor together with the suspended mower thereon must be backed up in order to be freed from an obstacle.
Further known from German Pat. No. 749 281 is a swinging cutting device for a tractor mower, which is pointed behind the tractor at an angle to the forward direction. Upon striking an obstacle then the mowing unit swings backwards with the cutting device about a perpendicular pin horizontally a small amount, which results by means of the sliding or transverse motion fixed by two kinds of sliding rods coupled together.
With this known cutting unit, after overcoming the obstacle, the cutting unit must be returned by the driver by hand to its original mowing position.
Furthermore spring biased safety apparatus for mowers is known which permits a release and return swing of the machine whenever an obstacle is encountered. This safety apparatus is customarily initiated by hand before mowing begins. This introduces the disadvantage that the operating person must stand between the rear of the tractor and the mower unit in order to operate the safety member. This introduces a significant danger of accident.
If one of these known safety mowers strike an obstacle with too heavy a blow, then the safety element is prevented from reaching its attainable force and the mower swing is stopped until a blow is encountered in its transport position. By permitting a blow of very high force to appear during the movement stroke, a single part can be destroyed.